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Sound Reinforcement - Forums for Live Sound Professionals - Your Displayed Name Must Be Your Real Full Name To Post In The Live Sound Forums => SR Forum Archives => LAB Lounge FUD Forum Archive => Topic started by: Mario Salazar on March 01, 2007, 04:15:04 pm

Title: Is +3db twice as loud?
Post by: Mario Salazar on March 01, 2007, 04:15:04 pm
Just heard this from EAW tech support when I asked why I would want to spend a bunch of money for just a +3db gain.  Is this true?  I thought it was +6db but I have learned so much on this site that I thought I knew so I thought I would ask.
Regards,
Mario
Continously being humbled on this site.
Title: Re: Is +3db twice as loud?
Post by: Mac Kerr on March 01, 2007, 04:23:46 pm
No, +3dB is twice as much power. The smallest difference in level that most people easily perceive is 3dB. Double the apparent loudness is more like 10dB.

Mac
Title: Re: Is +3db twice as loud?
Post by: dave stojan on March 01, 2007, 04:37:00 pm
Mac Kerr wrote on Thu, 01 March 2007 21:23

No, +3dB is twice as much power. The smallest difference in level that most people easily perceive is 3dB. Double the apparent loudness is more like 10dB.

Mac


I think by definition 1 db is the smallest difference for most people whereas 3db is quite noticeable. Double / half is generally accepted at 10db although it appears that it has much to do with the nature of the sound and the relative move compared with the absolute level, and I've read sources touting as little as 6db change can be described as twice/half the volume under the right circumstances.

I have a CD player remote that allows me to change the volume in +/- 1db steps and sure enough, the 1 db is hard to discern under much program material but 3db is very noticeable. Should we call it a day at 2db?  Shocked

Title: Re: Is +3db twice as loud?
Post by: Mac Kerr on March 01, 2007, 04:49:30 pm
dave stojan wrote on Thu, 01 March 2007 16:37

Mac Kerr wrote on Thu, 01 March 2007 21:23

No, +3dB is twice as much power. The smallest difference in level that most people easily perceive is 3dB. Double the apparent loudness is more like 10dB.

Mac


I think by definition 1 db is the smallest difference for most people whereas 3db is quite noticeable. Double / half is generally accepted at 10db although it appears that it has much to do with the nature of the sound and the relative move compared with the absolute level, and I've read sources touting as little as 6db change can be described as twice/half the volume under the right circumstances.

I have a CD player remote that allows me to change the volume in +/- 1db steps and sure enough, the 1 db is hard to discern under much program material but 3db is very noticeable. Should we call it a day at 2db?  Shocked
I'm willing. I think that using soundmen who are trained to hear subtle differences in sound as the guide is unfair however. That is why I said "smallest difference in level that most people easily perceive". In any case, it's not double the apparent loudness.

Mac
Title: Re: Is +3db twice as loud?
Post by: Ales Dravinec 'Alex' on March 01, 2007, 05:02:56 pm
Quote:

....Should we call it a day at 2db?  Shocked ....


Dave, that's a good one !  Laughing

Alex
Title: Re: Is +3db twice as loud?
Post by: Michael 'Bink' Knowles on March 01, 2007, 05:21:52 pm
Quote:

...I think by definition 1 db is the smallest difference for most people...


Neither the decibel nor the Bel were standardized with reference to the just noticeable difference in human perception relative to sound level. The Bel came into being as a quantification of the reduction in audio level over a 1 mile (1.6 km) length of standard telephone cable. It was first called a Transmission Unit or TU.

Just by chance 1dB is roughly equal (depending on conditions) to the ability of listeners to detect a level difference. Trained subjects tested in a psychophysics lab with specific test sounds score better (lower) than 1dB.

http://en.wikipedia.org/wiki/Decibel
http://en.wikipedia.org/wiki/Just_noticeable_difference

-Bink
Title: Re: Is +3db twice as loud?
Post by: Mario Salazar on March 01, 2007, 05:22:23 pm
OK, I was sick of being ignorant so I spent the last 2 hours searching and I found my Yamaha book.  I am going to read this thing again and bring myself up to speed.  I used to know the information on this back and forth about 12 years ago, since then disinformation (like that I just got from EAW, (For shame))and time away from the business has dulled what used to be an acute understanding.  In case anybody else does a search on this here is what the handbook says:

Quoted fromthe Yamaha Sound Reinforcement Handbook "It turns out that a sound which is 3 dB higher than another is barely perceived to be louder; a sound which is 10 dB higher in level is perceived to be twice as loud."  

Accordingly, I don't think I will be paying much more to provide power that will only be perceived as very slightly louder.
Thanks for the responses guys!
It was, as always, greatly appreciated.
Best Regards,
Mario
Title: Re: Is +3db twice as loud?
Post by: Mike Butler (media) on March 01, 2007, 06:39:36 pm
In any case, there you have an object lesson in how quickly the slope steepens when striving to upgrade audio system performance.
Title: Re: Is +3db twice as loud?
Post by: Tony "T" Tissot on March 01, 2007, 06:42:46 pm
Mike Butler (media) wrote on Thu, 01 March 2007 15:39

In any case, there you have an object lesson in how quickly the slope steepens when striving to upgrade audio system performance.

Now we should talk about how slippery that slope is as well Razz
Title: Re: Is +3db twice as loud?
Post by: Steve Devino on March 01, 2007, 06:52:08 pm
Michael 'Bink' Knowles wrote on Thu, 01 March 2007 17:21

Quote:

...I think by definition 1 db is the smallest difference for most people...


Neither the decibel nor the Bel were standardized with reference to the just noticeable difference in human perception relative to sound level. The Bel came into being as a quantification of the reduction in audio level over a 1 mile (1.6 km) length of standard telephone cable. It was first called a Transmission Unit or TU.

Just by chance 1dB is roughly equal (depending on conditions) to the ability of listeners to detect a level difference. Trained subjects tested in a psychophysics lab with specific test sounds score better (lower) than 1dB.

http://en.wikipedia.org/wiki/Decibel
http://en.wikipedia.org/wiki/Just_noticeable_difference

-Bink



These guys must be all my studio customers who comment that they think the mix needs .1 dB more 2k etc   Smile


Steve

Title: Re: Is +3db twice as loud?
Post by: W. Mark Hellinger on March 01, 2007, 08:51:00 pm
Admittedly:

1)  +3dB is twice the power, and:
2)  +10dB is perceived as twice as loud, but:

Twice as much PA is generally perceived as "bigger" (even if the delivered SPL is about the same).

Oftentimes, a winning strategy is to strive for performances to come across as "bigger than life".  Sound, lights, props, stage presence all contribute to this.  PA gear can be some of the cheapest and most readily accessible props.  It all depends on the motif you're trying to achieve.  Rarely is gross amounts of SPL a major selling point in a show, but a lot of cone drivers tickled sounds "bigger" than fewer cone drivers straining their guts out.  And impressive rack & stacks generally look like a serious show.
Title: Re: Is +3db twice as loud?
Post by: dave stojan on March 01, 2007, 08:57:30 pm
Mario Salazar wrote on Thu, 01 March 2007 22:22

 Quoted fromthe Yamaha Sound Reinforcement Handbook "It turns out that a sound which is 3 dB higher than another is barely perceived to be louder;"  

Accordingly, I don't think I will be paying much more to provide power that will only be perceived as very slightly louder.



If you search the LAB archives you'll find the Yamaha Handbook has been pointed out incorrect on this particular subject. Think about it - if 3db is barely noticeable how would 10db sound twice as loud? Got a mixer? Move the fader 3db & listen to the difference. Oh, and that extra power your saving money on just might be the difference in clipping & blowing your speakers or not. Yeah, the diminishing returns kick in early and get worse on the way up, but things take what they take and like thermodynamics, you never get away cheap. And don't believe everything you read.  Surprised
Title: Re: Is +3db twice as loud?
Post by: drewgandy on March 01, 2007, 09:26:15 pm
Mario Salazar wrote on Thu, 01 March 2007 16:22

OK,

Accordingly, I don't think I will be paying much more to provide power that will only be perceived as very slightly louder.
Thanks for the responses guys!
It was, as always, greatly appreciated.
Best Regards,
Mario


A good look at the equal loudness contours might be in order.  If you look at the lines in the bass you'll find that they are quite close together.  I interpret this to mean that in the lower freqs it doesn't take as big a difference to appear to be much louder.  This seems to correlate with my experience with subs.  Often the difference between one sub and 2 is only really 6db but the change in perceived impact is really significant.  I wonder if the non-hearing physical sensations are more linear in perception.  
Title: Re: Is +3db twice as loud?
Post by: Bruce Gering on March 01, 2007, 09:43:12 pm
While 3dB may not be very noticeble in terms of overall loudness to the average listener, 3db more headroom in a system will certainly be noticed for it's improved clarity. I'll take the added headroom.
Title: Re: Is +3db twice as loud?
Post by: Mario Salazar on March 01, 2007, 10:15:04 pm
That was something I was considering, the headroom.  So maybe it is worth it. I don't know. I know that I will never hit the reds on the amps because my limiter is set up to stop this.  I know my gain structure well and know how far to go on the main fader.  The limiter just catches transients that may cause fast cliping. I have checked out the difference with my mixer and the yammy book seems correct.  While I can notice a difference at 1 db, there is only a slight difference at 3 db.  At 6 db I notice a significant change and at 10 db it does sound twice as loud.  Maybe I will save and search for a plx1802 here and there and buy them when I can.  I know I can use the 3402 for another two monitor mixes for my sm122s.  I am just scared that the power consumption might be a problem in smaller sound venues where their power supply is questionable.  I am still trying to learn the basics of power distros.  If I could figure this out and get one I would have less worries.
Thanks!
Title: Re: Is +3db twice as loud?
Post by: Miguel Castro Rios on March 02, 2007, 02:32:36 am
The 3 db question. . .  Shocked


You got to think, '' 3 db, at what frequency?''

While you may think this is not very important, try moving the eq at 4k by +/-3 db.- Now try it at 250 hz.

The reason why a bigger PA sounds BIGGER, it's because the drivers are not being pushed as hard as a smaller PA, making the sound cleaner. So If you only gain 3db with twice the speakers, you got to think, you are not ONLY gaining 3 db, BUT 3 NICE db's..- if that makes any sense.

Now what to some people may seem as 10 db twice as LOUD, to some one else may be only 6db. Yes it's psychological, and depends how much hearing loss you've had over the years. Majority rules, if 10 db is it, then let it be! Laughing

Title: Re: Is +3db twice as loud?
Post by: Elliot Thompson on March 02, 2007, 04:56:20 am
The easiest way I've narrowed it down, is using amplifier power.

All measured @ 1 Khz, 0.1 % THD


250 Watts @ 8 ohms

500 Watts @ 8 ohms

800 Watts @ 8 ohms

1000 Watts @ 8 ohms

Going from 250 to 500 will yield a 3 dB gain

Going from 250 to 1000 will yield a 6 db gain

Going from 500 to 800 will yield a 2 dB gain

Going from 500 to 1000 will yield a 3 dB gain


I generally go no lower than 3 dBs when upgrading amplifiers. While 2 dB is noticable, it's generally not worth the money invested in the upgrade. I think many don't understand you really need to focus on the difference under 3 dB which, may not be the object behind upgrading from a 500 watt amplifer to a 800 watt amplifier.

Pretty much like comparing a QSC PLX 3002 versus a PLX 3402.
Bridging both amplifiers @ 4 ohms yields a 0.5 dB gain in favor of the 3402. You won't hear a difference, at 0.5 dB gain.

Best Regards,

Title: Re: Is +3db twice as loud?
Post by: Brad Weber on March 02, 2007, 02:19:38 pm
dave stojan wrote on Thu, 01 March 2007 20:57

If you search the LAB archives you'll find the Yamaha Handbook has been pointed out incorrect on this particular subject. Think about it - if 3db is barely noticeable how would 10db sound twice as loud?
Then just about every other respected audio and acoustics text and reference must also be wrong.

You have to keep in mind that what is being addressed is perceived changes in loudness due to changes in sound levels, not signal levels.  Human hearing is not linear in frequency or level nor in the perception of several other factors, thus perceived loudness becomes very complex where absolute level, frequency content, tonal components and duration among other factors can affect the perceived loudness.  So assessing changes in loudness is quite different than addressing absolute voltage or power level changes.  I think that trying to consider a big picture that can encompass voltage levels, electrical and sound power levels, sound pressure levels and loudness levels quite understandably confuses many people.

For one thing dB numbers, such as dB Sound Pressure Levels or dBV and dBu, are ratios derived by referencing one number to another reference number, the term "dB" by itself is actually meaningless without some reference value.  Conversely, loudness is actually measured in absolute units of phons and sones rather than in dB units.  But more importantly, what is actually being related to the effect on loudness is not a change in the voltage or electrical signal level but rather a change in acoustical Sound Pressure Levels (SPL).  Trying to relate a specific change in a fader level directly to a change in perceived loudness is not really a valid relationship as there are numerous factors that can keep this from being a direct, much less linear, relationship.

What is generally stated is that all else being the same, a change in Sound Pressure Level of 3dBSPL is perceived as a readily noticeable change in loudness, while a 10dBSPL change in level is perceived as a halving or doubling in loudness.  I think that this generalization is usually applied in the context of trying to create the same signal, only louder or softer, and in that sense it is valid.  If there are differences in the frequency content, duration, etc. fo the acoustical signal then this generalization certainly may not be true, but I think that is somewhat beyond the issue at hand.
Title: Re: Is +3db twice as loud?
Post by: dave stojan on March 02, 2007, 03:35:15 pm
Brad Weber wrote on Fri, 02 March 2007 19:19

What is generally stated is that all else being the same, a change in Sound Pressure Level of 3dBSPL is perceived as a readily noticeable change in loudness, while a 10dBSPL change in level is perceived as a halving or doubling in loudness.  I think that this generalization is usually applied in the context of trying to create the same signal, only louder or softer, and in that sense it is valid.  If there are differences in the frequency content, duration, etc. fo the acoustical signal then this generalization certainly may not be true, but I think that is somewhat beyond the issue at hand.


Thank you for agreeing with me  Very Happy
Title: Re: Is +3db twice as loud?
Post by: John Roberts {JR} on March 02, 2007, 04:11:26 pm
I believe this may have already been mentioned but the Bel was a very specific power measurement unrelated to anything subjective or perceived. The decibel (1/10 Bel) came into popular use because it was considered a convenient incremental value.

Correlation between 1 or several dB and perceived loudness changes are somewhat listener or program specific. These approximate relationships are useful when sizing systems but not very precise.

I have a great deal of difficulty visualizing or hypothesizing loudness as something I can assign proportionate values to. "Um does that sound 20% louder or 25%?" But that may just be a personal problem as many apparently form such opinions without much difficulty. Perhaps it's easier if you use a large quantum (i.e. twice as loud). But if you can't quantify smaller ratios, how precise can you be about the larger?  Whatever. Rolling Eyes

JR

PS: Perhaps for use with modern electronic instrumentation a centi-Bel might be useful.  
Title: Re: Is +3db twice as loud?
Post by: Brad Weber on March 02, 2007, 05:10:23 pm
Okay, now I get it.  You are playing with the semantics regarding the terms "barely", "clearly" and "readily" that have no definitive reference and are open to interpretation.  That was not clear from your earlier post where you stated that the book was incorrect on the subject rather than indicating that your issue was actually the specific terminology used.  What is really the important point is simply that it is a noticeable or perceptible difference to most people, adding other adjectives may just be confusing the point.  

Quote:

Think about it - if 3db is barely noticeable how would 10db sound twice as loud? Got a mixer? Move the fader 3db & listen to the difference.
3dB on a fader is not 3dBSPL and relating those as seemed to be done is wrong.  There are many factors that could make even any indirect relationship nonlinear.  The fact is that "3dB" and "10dB" are actually completely meaningless terms by themselves and using dB without noting the application and reference, much less mixing different dB references such as dBSPL and dBV/dBu, is very poor practice and leads to many misunderstandings.  If we are going to worry about the nuances of the language used, then we probably should to show the same concern when referencing dB and levels.

If I remember correctly, 1 sone = 40 phons = the loudness of a 1kHz pure tone at 40dBSPL re: 20 micropascals.  A 10dBSPL increase in the level of the 1kHz tone doubles the sone level, thus the general concept that a difference of 10dBSPL is perceived as a doubling of loudness.  Of course all of this is based on research into the perception of sound by individuals, so the general results really only apply to some mythical generic person and will vary from person to person.
Title: Re: Is +3db twice as loud?
Post by: Lee Patzius on March 03, 2007, 12:34:23 pm
index.php/fa/8191/0/
Title: Re: Is +3db twice as loud?
Post by: Michael 'Bink' Knowles on March 03, 2007, 01:39:13 pm
Cool, Lee. What's that chart from?

-Bink
Title: Re: Is +3db twice as loud?
Post by: Lee Patzius on March 03, 2007, 05:19:21 pm
Michael 'Bink' Knowles wrote on Sat, 03 March 2007 13:39

Cool, Lee. What's that chart from?

-Bink


Hi Bink,

I got it from here:

http://www.gcaudio.com/resources/howtos/voltageloudness.html
Title: Re: Is +3db twice as loud?
Post by: Mario Salazar on March 03, 2007, 10:36:46 pm
WOW, looks like the topic has gotten a bit contentious, but in the end we seem to agree.  Thanks for the chart.  Looks like that 3dB will give me 23% more loudness.  I think I will look out for the amps and buy them just to know that I have my system maxed out.  Thanks for the Chart Lee and thanks to all others who have provided their input.
I really appreciate it!
Best Regards,
Mario